1 /*
2 * Copyright 2022 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <stdlib.h>
18
19 static const char *TAG = "SimpleNoiseMaker";
20
21 #include <android/log.h>
22
23 #include <SimpleNoiseMaker.h>
24
25 using namespace oboe;
26
open()27 oboe::Result SimpleNoiseMaker::open() {
28 // Use shared_ptr to prevent use of a deleted callback.
29 mDataCallback = std::make_shared<MyDataCallback>();
30 mErrorCallback = std::make_shared<MyErrorCallback>(this);
31
32 AudioStreamBuilder builder;
33 oboe::Result result = builder.setSharingMode(oboe::SharingMode::Exclusive)
34 ->setPerformanceMode(oboe::PerformanceMode::LowLatency)
35 ->setFormat(oboe::AudioFormat::Float)
36 ->setChannelCount(kChannelCount)
37 ->setDataCallback(mDataCallback)
38 ->setErrorCallback(mErrorCallback)
39 // Open using a shared_ptr.
40 ->openStream(mStream);
41 return result;
42 }
43
start()44 oboe::Result SimpleNoiseMaker::start() {
45 return mStream->requestStart();
46 }
47
stop()48 oboe::Result SimpleNoiseMaker::stop() {
49 return mStream->requestStop();
50 }
51
close()52 oboe::Result SimpleNoiseMaker::close() {
53 return mStream->close();
54 }
55
56 /**
57 * This callback method will be called from a high priority audio thread.
58 * It should only do math and not do any blocking operations like
59 * reading or writing files, memory allocation, or networking.
60 * @param audioStream
61 * @param audioData pointer to an array of samples to be filled
62 * @param numFrames number of frames needed
63 * @return
64 */
onAudioReady(AudioStream * audioStream,void * audioData,int32_t numFrames)65 DataCallbackResult SimpleNoiseMaker::MyDataCallback::onAudioReady(
66 AudioStream *audioStream,
67 void *audioData,
68 int32_t numFrames) {
69 // We requested float when we built the stream.
70 float *output = (float *) audioData;
71 // Fill buffer with random numbers to create "white noise".
72 int numSamples = numFrames * kChannelCount;
73 for (int i = 0; i < numSamples; i++) {
74 // drand48() returns a random number between 0.0 and 1.0.
75 // Center and scale it to a reasonable value.
76 *output++ = (float) ((drand48() - 0.5) * 0.6);
77 }
78 return oboe::DataCallbackResult::Continue;
79 }
80
onErrorAfterClose(oboe::AudioStream * oboeStream,oboe::Result error)81 void SimpleNoiseMaker::MyErrorCallback::onErrorAfterClose(oboe::AudioStream *oboeStream,
82 oboe::Result error) {
83 __android_log_print(ANDROID_LOG_INFO, TAG,
84 "%s() - error = %s",
85 __func__,
86 oboe::convertToText(error)
87 );
88 // Try to open and start a new stream after a disconnect.
89 if (mParent->open() == Result::OK) {
90 mParent->start();
91 }
92 }
93